The oily or fatty mixtures originate from fats and fatty oils of biological origin, i.e. from plant, animal or microbial origin, and are known to be mixtures of different ingredients.
Fats and fatty oils are mixtures where esters of glycerol with three mostly different, predominantly even-numbered and unbranched aliphatic mono carboxylic acids, the fatty acids, make up the majority of the mixture. Compounds of this type are also called triglycerides. In addition to the glycerides fats and fatty oils contain accompanying substances that are usually grouped together in the technical literature as “unsaponifiable fractions”. These are ingredients of the so-called plant secondary metabolism, including vitamin E, sterols and/or terpenes.
Depending on whether the compound mixture is solid or liquid at room temperature, it is called fat or fatty oil. Most fats are the eponymous compositions from different fatty acid triglycerides, which are obtained from animals. The term fatty oil distinguishes the (thin) fluid mixtures of materials of biological origin from other groups of oils, for example, from the liquid hydrocarbons.
Fats and fatty oils from biological origin are obtained either from animal products, from plants or from micro-organisms, such as bacteria or yeasts but also from algae or fungi. Animal fats can be melted directly from adipose tissue and apply as lard, blubber or tallow, or can be obtained from milk. The vegetable oils and fats used for food can be obtained from oil plants or oilseed by pressure or by extraction with steam, supercritical CO2 or solvents. Refining removes unwanted ingredients and refined fats or fatty oils are thereby graded up for use.
Newly substantial amounts of vegetable oils, particularly rapeseed oil or palm oil, are chemically reacted to biodiesel. For this purpose the oils are submitted to a transesterification with methanol in the presence of mostly alkaline catalysts, whereupon fatty acid methyl esters (FAME) and glycerol are formed. The former can be used directly as biodiesel or are mixed with conventional fuel. Furthermore, soaps, the alkali salts of fatty acids, can be produced by alkaline hydrolysis of fats or fatty oils. Thereby also glycerol accumulates as a secondary component.
The use of fats and fatty oils as food and in the making of food as well as in the preservation of food is widespread.
Native fats and fatty oils directly after pressing are often not suitable for direct consumption and must be released in a pre-cleaning from bitterns, free fatty acids, dyes and other undesired accompanying substances affecting taste and aesthetics. This is achieved by using two different techniques, referred to as chemical or physical refining. Today, in the vast extent the physical purification to edible oils is preferred due to economic considerations. Under high pressure, hypertensive water vapor at temperatures above 200° C. is guided through the oil to be cleaned. In doing so the water vapor entrains all volatile portions that after condensation and pressure relaxation can be attained as so-called deodorization distillates. In the literature these “waste components” are designated as oleo-waste, as DDO (“Deodorization Distillates Oils”), as condensates (“Oil Physical Refining Condensate” or “OPRC”) or in the predominate case in the English-speaking world as FAD (“Fatty Acid Distillates”).
“Oily and fatty mixtures” are understood in terms of the invention as fats and fatty oils of biological origin but also as the “waste components” denominated in the preceding, in particular DDO and OPRC, but also waste components of fats and oils, which are accumulated in the food industry and gastronomy.
The “unsaponifiable fractions” contained in the oily and fatty mixtures are ingredients of the so-called secondary metabolism, especially of plant secondary metabolism. These chemically and functionally very different compounds are called “secondary ingredients” in the remainder of this description. Chemically considered these secondary ingredients are complicated olefinic, aliphatic or aromatic alcohol components or terpenes, which display different physiological effects in plants but also in animals.
A very valuable portion of this substance group not only for human physiology are the vitamins of the E-series. The basic structure of all forms of vitamin E forms a chromane ring hydroxylated at position 6, whose methylation divides these into a α-, β-, γ- or δ-form. Two main families are distinguished by side chains of different saturation, namely the saturated tocopherols and the triple unsaturated tocotrienols. Also additional species (tocomonoenols), which can be denominated rather than exotic, can be included in the vitamin E.
Vitamin E is a component of all animal cell membranes, is however made only by photosynthetic active organisms such as plants and cyanobacteria, and must be ingested therefore by animals and humans through food. Out of the eight most important representatives of the naturally occurring vitamin E series α-tocopherol is the substance with the strongest physiological effect and therefore also with the greatest technical and economic importance. The individual members of the tocopherol family differ in the degree of methylation of their benzene nucleus or in the case of tocotrienols in the degree of saturation of the side group.
Especially high concentrations of vitamin E are contained in vegetable oils like wheat germ oil (up to 2435 mg/kg total tocopherol with 70% α-tocopherol), sunflower oil (454-810 mg/kg total tocopherol with 86-99% α-tocopherol), red palm oil (800 mg/kg total vitamin E, of which 152 α-tocopherol and 600 mg/kg tocotrienols) and olive oil (46-224 mg/kg total tocopherol with 89-100% α-tocopherol). The dose- and matrix-dependent absorption rate is on average at 30%.
Vitamin E is also synthetically produced as a racemic mixture (among others by BASF, E. Merck (India) and DSM Nutritional Products). Synthetic tocopherol is relatively unstable and is provided thereby mostly with an acetyl group (see also dl-α tocopheryl acetate). This does not have antioxidant properties. But it can be converted in the body to the extent of up to 50% into natural vitamin E.
Just as valuable components of the unsaponifiable fraction of oily or fatty mixtures of fats and fatty oils of biological origin are sterols, which are important biochemical natural products for the pharmaceutical, cosmetics and food industry. The sterols—also called sterines—are an important subgroup of steroids. Basic framework is the sterine, a sterane with a 3β-hydroxyl group. Depending from their occurrence sterins can be divided in zoo sterols (from animals), phytosterols (from plants) and mycosterines (from fungi). Important zoo sterols are cholesterol and coprosterine that is formed by bacteria from cholesterol in the intestine. Stigmasterine (stigmasterols) occurring in soybeans, camposterine (camposterol) and also sitosterine (sitosterol) are counted among the phytosterols. Several phytosterols occur also in wheat seedlings. Counted among the group of mycosterines is e.g. ergosterine (ergosterol) isolable from yeasts, which is closely related to the vitamines of the D series.
Terpenes are another group of secondary ingredients that occur in fats and fatty oils of biological origin and that belong to the unsaponifiable fraction. This substance class, that is separable through the process of the invention, is a very large and highly heterogeneous group of chemical compounds which occur naturally in many organisms. They formally derive from isoprene and are characterized by a great variety of carbon frameworks with functional groups. Most of the terpenes are of vegetal origin and seldom of animal origin. Predominantly hydrocarbon-, alcohol-, glycoside-, ether-, aldehyde-, ketone-, carboxylic acid- and ester-terpenes occur in nature, but also representatives of other groups of substances can be found among the terpenes.
Terpenes are often of biological and pharmacological interest. They can be used e.g. as environmentally friendly insecticides in that they lure insects into traps as pheromones. In addition, many operate anti-microbial. Many terpenes are used in perfumes and cosmetic products as odors or flavors.
In the context of the present description among terpenes hydrocarbon compounds and also oxygenous isoprene derivatives are understood, whereupon the latter are sometimes also designated as terpenoids.
Terpenes are counted among the lipids in the systematics of organic chemistry. The affiliation to the terpenes is based in a common biosynthesis and in the C5 rule, but not in common properties. Common building block of all terpenes is isoprene.
Generally one distinguishes between acyclic, mono-, bi-, tri-, tetra- and pentacyclic terpenes, thus molecules without, with one, two, three, four or five rings. Furthermore, terpenes can be differentiated by the carbon framework on which they are built. Also, they are classified through their secondary affiliation of element groups.
Terpenes can be divided into isoprene units, which have the same number of carbon atoms. Terpenes with 5 carbon atoms are called hemiterpenes (C5), with 10 mono-terpenes (C10), with 15 sesquiterpenes (C15), with 20 diterpenes (C20), with 25 sester terpenes (C25), with 30 triterpenes (C30), and with 40 tetraterpenes (C40). Terpenes with more than 8 isoprene units, thus with more than 40 carbon atoms are called poly terpenes (greater than C40). Here, the isoprene unit is counted as half a terpene.
Squalene is a particularly preferred terpene. It is an unsaturated organic compound with the molecular formula C30H50 from the group of triterpenes produced by all higher organisms. The compound is an integral part of skin lipids and is also found in the human blood serum. Squalene is present in high concentration levels in different foods, such as in goat's milk and in many vegetable oils, such as olive oil, wheat germ oil or rice bran oil. Fish oils are the main resources. Squalene is used industrially and is hydrogenated to squalane, which is used as a basis for ointments as well as a lubricant and a transformer oil.
Preferred sources of these secondary ingredients are particularly oils and fats of vegetable origin, in particular acai oil, algae oil, apricot kernel oil, argan oil, avocado oil, babacu oil, cotton seed oil, ben oil, borage oil, nettle seed oil, cashew shell oil, cupuaçu butter, thistle oil, peanut oil, safflower oil, hemp oil, rosehip seed oil, hazelnut oil, jathropha oil, jojoba oil, coffee bean oil, cocoa butter, camellia oil, coconut oil, cumin oil, pumpkin seed oil, linseed oil, cameline oil, macadamia oil, corn oil, almond oil, mango butter, poppy-seed oil, evening primrose oil, olive oil, palm oil, palm kernel oil, papaya seed oil, pecan oil, perilla oil, pistachio oil, rapeseed oil, rice oil, castor oil, sea buckthorn seed oil, sea buckthorn oil, black cumin oil, mustard oil, sesame oil, shea butter, soybean oil, sunflower oil, grape seed oil, tung oil, walnut oil, watermelon seed oil or wheat germ oil.
Depending on the origin, vegetable fatty oils or fats contain a proportion of non-saponifiable secondary ingredients of about 0.5 to 5% by weight, animal fat oils or fats a lesser proportion, to which vitamin E, terpenes and sterols are counted.
Deodorization distillates (DDO or OPRC) contain higher levels of secondary plant ingredients.
To separate these non-saponifiable components of fatty acids and glycerides (fat components) different methods are available, such as disclosed in “The Encyclopedia of Vitamin E, ISBN 978-1-84593-075-2, pp. 140-141. A common method for the separation of the fat components from tocopherol is the esterification of free fatty acids followed by a transesterification step with subsequent distillative separation of the esters.
State of the art is that fatty acids and glycerides are transferred into fatty acid methyl esters by esterification of the fatty acids and by transesterification of the glycerides with short-chain alcohols, preferred with methanol, which can be isolated by distillation. An esterification of fatty acids and a transesterification of glycerides does not succeed in conventional procedures in a single reaction step, but requires the esterification of the fatty acid in a first step and the transesterification of the glycerides in a subsequent step.
The transesterification of the glycerides is normally performed in alkaline medium, because the reaction speed in the acidic environment is much too low and requires significantly more drastic conditions. The presence of alkaline reagents leads but to the neutralization of free fatty acids and disrupts the transesterification reaction of the glycerides (partial saponification). For this reason in practice an acid esterification of the free fatty acid content is operated beforehand, as described in the following patent.
U.S. Pat. No. 5,190,618 teaches to separate the non-saponifiable components from the glycerides and the free fatty acids in that in a first step the free fatty acids are esterified with a short-chain alcohol, for example with methanol, in the presence of an acid catalyst, for example p-toluene sulfonic acid, at 65 to 110° C., and in a second reaction step the glyceride portions are transesterified with a short-chain alcohol, e.g. methanol, in the presence of an alkaline catalyst, for example sodium methoxide, at 30 to 70° C. and the obtained fatty acid alkyl esters are distilled off. The tocopherol and tocotrienol enriched in the residue is obtained in high concentrations by crystallization, ion exchange processes and distillation. This procedure is very laborious and also has the disadvantage that tocopherol and the sterols also present under the chosen reaction conditions in the acid medium are very easily esterified with free fatty acids. In the therefore necessary alkaline reaction section these esters are then split subsequently into the free components again, however there will be a very noticeable degradation of the tocopherol due to its oxidative instability in the basic environment.
U.S. Pat. No. 5,487,817 discloses a method for the isolation of tocopherol and sterols from a mixture consisting essentially of tocopherol, sterols, fatty acids and glycerides. In the process the sterols are esterified in the course from 1 to 12 hours at 150 to 250° C. without acidic or alkaline catalysis and remnants of fatty acid, tocopherol and sterol fatty acid esters are separated by several distillation steps at 150 to 220° C. under vacuum.
The sterol fatty acid esters contained in the residue are transesterified by acid catalysis and are isolated from the glyceride. It is known (Acta Agric Scan 35: 136-138 (1985)), that temperatures above 120° C. result in significant degradation of tocopherol, whereby the yields of tocopherol are reduced. Also, a smaller amount of tocopherol is esterified in this procedure in the presence of fatty acids, and this causes a further loss of vitamin E. Likewise, sterols are temperature- and light-sensitive and are destroyed in part under the conditions.
EP-A-2,448,905 describes a continuous process for producing aliphatic carboxylic acid esters by reaction of aliphatic carboxylic acids with alcohol in the presence of an esterification catalyst under exposure to microwave radiation.
WO-A-2011/035853 describes a continuous process for producing fatty acid methyl esters through transesterification of fatty acid esters of multi-valent alcohols, in particular glycerides, with methanol in the presence of alkaline or acidic catalysts under exposure to microwave radiation. The procedure allows the production of high-purity fatty acid methyl esters from native fats and oils in large scale processes, or from the waste products from their refining, even in the presence of free acids. Procedures for the isolation of other ingredients from the native oils or fats or from the waste products of native oils or fats is not the subject of the invention.
The methods for the separation of non-saponifiable ingredients from DDO's or OPRC's referred to in the prior art are energy intensive and are unsatisfactory regarding the yield of the physiologically particularly valuable secondary ingredients, such as vitamin E, especially α-tocopherol, tocotrienols, sterols and terpenes.